The wheel end area of a vehicle is an area having many structures and systems important for vehicle operation and performance. For example, structures and systems relating to vehicle braking, vehicle suspension, vehicle steering and vehicle drive, may all be found in the wheel end area. Those skilled in the art will appreciate that some or all of these structures and systems must co-exist in the same general wheel end area. Additional structures and systems, such as wheel performance sensors and tire inflation systems, must fit in this same area also. Various prior art systems are known that teach sensors and/or tire inflation systems, however, such systems have not yet efficiently combined the two to minimize the space they occupy.
For example, U.S. Pat. No. 6,435,238 teaches a tire inflation system located in a vehicle axle. A fitting is secured to an air passage tube extending through the hub cap. The fitting has a stationary rotary seal for sealing the fitting to the tube. A separable component from the fitting engages an air supply tube that extends through the axle. A speed sensor assembly is also taught, however, the rotor of the sensor is located radially outward from the axle. The stator of the assembly is located within the axle.
U.S. Pat. No. 6,585,019 provides for a tire inflation system comprising a shaft extending through a hub cap. One end of the shaft is connected to an air hose. The other end of the shaft is connected to a rotary housing. A pair of bearings is mounted within the housing to allow the housing to rotate on the shaft. A reduced diameter portion of the rotary housing projects through a centrally disposed aperture in the end wall of the hub cap. The rotary housing is sealably secured against the exterior end wall of the hub cap. A wheel speed sensor is not taught.
U.S. Pat. No. 6,575,269 teaches a wheel bearing located between a wheel support and a hub. The hub is driven by a drive shaft housed within the hub. Inflation and deflation of a tire occurs via a connecting member through channels and/or bores in the wheel support. Additional channels and/or bores provide a fluid connection to a control valve mounted on the hub.
The prior art generally discussed above has several disadvantages. First, some prior art documents teach a sensor or a tire inflation system, but not both. Second, the prior art systems do not combine a wheel sensor with a tire inflation system so as to minimize the space used by these structures at the wheel end. Third, some prior art designs locate the sensing elements outside of the axle. These designs lead to increase costs since non-standard hub caps and additional hardware to center the sensing elements in the hub caps must be used. In light of the disadvantages of the prior art, it would advantageous to compactly combine a wheel speed sensor with a tire inflation system substantially within the vehicle axle.